Author
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Lenssen, Andrew |
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Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only Publication Acceptance Date: 5/23/2005 Publication Date: 8/25/2005 Citation: Lenssen, A.W. 2005. Preplant weed management and planting date influence barley forage yield and quality. ASA-CSSA-SSSA Annual Meeting. Available:http://crops.confex.com/crops/2005am/techprogram/P4367.htm. Interpretive Summary: Annual hay crops are well adapted to the Northern Great Plains, and are currently produced on 250,000 acres in Montana. A field trial was conducted comparing forage yield and quality, water use, and weed biomass, quality, and seed production in forage barley following three preplant weed management strategies. Preplant weed management strategies were conventional tillage, zero tillage with a herbicidal application of glyphosate, and zero tillage without a herbicide. Forage yields ranged from 1-3 tons per acre. Forage yield decreased with later planting dates. Weed biomass increased with later planting dates, especially for the zero tillage without herbicide treatment. Water use was similar between early and mid- planting dates, but decreased with later planting. Nutritive value of barley forage was excellent for all planting dates. Weed seed production did not occur before harvest of barley from the earliest planting date, regardless of preplant weed management. Conversely, at the last planting date, weed seed production occurred in all treatments, with the highest number of seed produced in the zero tillage planting without herbicide. This study documents the potential economical and environmentally sustainable annual forage crop production in the Northern Great Plains. Technical Abstract: Annual hay crops, including barley, are well adapted to dryland cropping systems in the Northern Great Plains. In-crop herbicides typically are not used on annual forages, but weed control is typically done prior to planting and after harvest, either with tillage or herbicide. A field trial was done comparing forage yield and quality, water use, and weed biomass, quality, and seed production in forage barley following three preplant weed management strategies over three planting dates near Froid, MT. Preplant weed management strategies were tillage with sweeps and rods (T), zero-tillage with glyphosate application (ZTG), and zero-tillage without herbicide (ZTC). Weed density at planting was 21, 387, and 389 plants m-2 for early, mid-, and late planting dates. Weed biomass at planting was 0.2, 1.8, and 9.1 g DM m-2 for early, mid-, and late planting dates. Across weed management treatments, delayed planting resulted in decreased barley production and water use, and increased weed biomass and seed production. Barley forage yields were 6.1, 4.5, and 3.0 mt ha-1, for early, mid-, and late planting dates. Water use was 194, 191, and 153 mm ha-1, for early, mid-, and late planting dates. Crude protein concentration of barley increased with later planting date, but neutral and acid detergent fiber concentrations were similar across dates. Conversely, protein concentration of weeds decreased with later planting dates. Early planted barley was harvested prior to any weed seed production regardless of weed management method. Green foxtail was responsible for 94% of weed seed production, with the greatest production, 8100 seed m-2, from ZTC at the third planting date. Production of early planted, zero-tillage forage barley without herbicide may be economically and environmentally sustainable in the Northern Great Plains. |
